Assailants on a motorcycle threw a grenade at the French embassy in Athens on Thursday, slightly wounding a police officer on duty, police said.
Greece's anti-terrorism police are investigating the attack, which happened at around 5 AM (local time) on one of the city's main avenues and opposite parliament.
Police are working on the theory that the attack was staged by local anarchists, who regularly carry out acts of violence against diplomatic missions.
Investigators have also not ruled out a link to the rise of the extreme right in France, following the congratulatory message by National Front leader Marine Le Pen to Donald Trump on his US election victory.
Government spokesman Dimitris Tzanakopoulos condemned the attack, insisting that "friendly relations between Greece and France cannot be influenced in the least by such terrorist acts."
The grenade left a tennis ball-sized hole in the pavement, and shrapnel marks on the embassy gate and guard post.
"Given the minor damage, it is likely a symbolic attack," a police source told AFP.
The officer added that police are inspecting for possible links a stolen motorcycle found a few kilometres away from the attack in Exarchia, a district popular with anarchists.
The injured police officer was taken to hospital where he received treatment for leg injuries.
It was not immediately clear if he was standing outside at the time of the attack, or if the door of the bullet-proof guardpost had been left open.